1. Field of the Invention
The invention relates generally to the field of keyboard wedge systems and processing of data streams, and more particularly to simplified configuration of barcode symbol scanning systems and processing of data streams therefrom.
2. Description of the Related Art
Barcode scanning systems have found an ever-increasing number of uses and applications. For example, barcoding has been utilized for inventory and warehousing applications, as well as with point of sale terminals. Many different types and complexities of barcodes systems have been used. A typical basic barcode symbol scanning system includes a barcode scanner, a decoder and a computer. The scanner and decoder have been utilized to retrieve information from barcodes for use by the computer system.
Conventional linear or one-dimensional barcodes have been in use since about 1970. The usefulness of such barcodes is limited by relatively small data capacity. To overcome this limitation, two-dimensional barcode symbologies have evolved. These symbologies are capable of encoding large amounts of data. For example, PDF417 barcode can encode up to 1800 ASCII characters or 2700 digits. However, in some applications only a portion of the scanned information is needed.
As part of a barcode reading system, a decoder is defined as an electronic package that receives a signal from the scanner, interprets the signal into meaningful data, and provides the data to other devices of the system. So far as known, there are three main types of decoders: wedge decoders, serial decoders and software decoders. Wedge decoders are systems that provide a decoding function for computer input. With keyboard wedge decoders, the data is decoded so that it appears as though it was manually typed or keyed directly into the computer. The basic function of keyboard wedge devices is conversion of scanned data into codes that are like those of keystrokes or keyboard data. Some keyboard wedge devices also have capability like that of software decoders to manipulate the scanned data, adding characters to the data stream or remapping the data stream altogether. However, to enable this data manipulation capability, the scanner must be manually pre-configured by scanning a multitude of special types of bar codes. This is a very complicated and time-consuming procedure.
Serial decoders are also external devices that connect into a communications or COM port of the personal computer. Typically, decoded scanners (i.e., scanners in which the decoder is integrated, usually into the handle of the scanner) are expensive.
Software wedges, located within the PC software, received the scanner data generally via the COM port. The received scanner data is then re-routed within the computer to the keyboard buffer. The data thus appears to other parts of the computer to have originated from the keyboard.
Many different types of scanning devices have been available. Scanning devices include wands, charge coupled device (CCD) scanners and laser scanners. Wand scanners tend to be the least expensive, followed by CCD scanners and laser scanners (the most expensive). Most scanning devices use a light emitting diode (LED) and a photo detector to scan barcodes. The light generated from the LED falls on the barcodes and is absorbed by the printed bars and reflected by the white spaces. The photodetector senses the reflected light and electro-optically converts the reflected light into a signal. The digitized signal is then sent to a decoder and converted into ASCII or other types of data characters.
Currently, there are more than 400 barcode symbologies in use. Each character in a barcode symbology is generally represented by a barcode in the form of a series of bars and spaces. Typically, each barcode symbol, as encoded, includes a quiet zone, start code or pattern, data characters, stop code and trailing quiet zone. Many symbologies support a check digit or digits to ensure data integrity. With such symbologies, the check digit or digits are usually located before the stop code. A barcode symbol is represented by a combination of barcode characters including the start/stop codes, quiet zones, data characters and check characters (as required by a particular symbology) that forms a complete, scannable entity.